Well into the twentieth century, many scientists believed the ocean floor was

In the 20th century, the scientist believed that the floor of the ocean floor is flat. But later on discovered that their theory is wrong. The ocean floor is not flat and featureless. One technology helped the scientist to study in advance and in details the real feature of the ocean floor. They used sound waves to know the distance of the water from floor level to the top. They also discovered that ranges of mountains lies under the ocean. Sonar was one of the technologies they used to study the sound waves emitted by the ocean.

This is all you, but i can give you some topics that you could try. if it rained when you want to do something outdoors, it 'limits' that human activity. maybe you want to do an experiment that goes throughout the whole year and you have to have above freezing the entire year. this 'limits' your activity. i thought of those just off of the top of my head. something that gets to me that might be getting to you is you are thinking too hard about what to do. think simply, and if it is too simple, then bump it up just a little bit.